Inkjet printing machines or printers include at least one printhead that ejects drops of liquid ink onto the surface of media. An inkjet printer employs inks in which pigments or other colorants are suspended in a carrier or are in solution with a solvent. The solvent may be water based, as in aqueous inks, or non-water based, as in non-aqueous inks. The amount of spread of ink drops ejected onto media affects the quality of the ink image formed. The spread of aqueous ink drops can be large enough to affect image quality adversely, particularly on coated media, such as papers having glossy, semi-glossy, or matte surfaces. These coated media are sometimes called offset paper and the interaction of aqueous ink with the surface of offset paper can be problematic. For example, aqueous ink ejected onto offset papers having glossy or semi-glossy surfaces often does not penetrate the media or get absorbed properly. The glossy or semi-glossy surfaces are water resistant because the surfaces have a relatively low porosity or permeability compared to uncoated papers. Consequently, the individual ink drops, which dry primarily by evaporation of water in the ink, slowly spread laterally across the surface of the coating before drying. If the drops are not dry enough and, consequently, are too mobile after they have joined with adjacent drops, a possibility exists of disturbing or moving the ink in these areas so the basic positions of these drops, the uniformity of the thickness of the inks at various positions, or both are affected. These conditions are commonly known as “coalescing” and “puddling” of the ink drops and noticeably impacts print quality. Because coalesced or puddled ink drops exhibit uneven thicknesses and drying characteristics they may also be undesirably transferred to other surfaces with which the media comes into contact, such as other paper in a sheet fed printing process. Moreover, when inks dry too slowly, two different colors of ink ejected adjacent each other tend to bleed into one another producing a defect known as “intercolor bleed.”
Another example of the interaction of aqueous ink with offset papers occurs with offset papers having a matte finish. This type of surface often absorbs too deeply into the paper. The matte surfaces are more porous than glossy paper, allowing for deeper penetration of ink, especially aqueous ink due to high water content. Accordingly, the printed image may lose color richness. Localized differences in the water content of media can also result in undesirable paper cockle. Thus, a system or method that reduces the spread of ejected ink drops in inkjet printers is desirable.